First, we need to equalize the denominator. If the denominator multiplies by (x+1), so does the numerator. If the denominator multiplies by (x-1), so does the numerator.
Look into my attachment at the second row.
Second, because the first fraction and the second fraction have the same denominator, you can join them into one fraction.
Look into my attachment at the third row.
Third, simplify the numerator.
Look into my attachment at the fourth to the fifth row
Fourth, simplify the denominator.
Look into my attachment at the sixth to the seventh row.